Butterflies and moths are subject to different evolutionary pressures that affect several aspects of their behaviour and physiology, particularly sexual communication. Butterflies are day-flying insects (excluding hedylids) whose partner-finding strategy is mainly based on visual cues and female butterflies having apparently lost the typical sex pheromone glands. Moths, in contrast, are mostly night-flyers and use female-released long-range pheromones for partner-finding. However, some moth families are exclusively day-flyers, and therefore subject to evolutionary pressures similar to those endured by butterflies. Among them, the Castniidae, also called ‘butterfly-moths’ or ‘sun-moths’, behave like butterflies and, thus, castniid females appear to have also lost their pheromone glands, an unparallel attribute in the world of moths. In this paper, we review the sexual communication strategy in day-flying Lepidoptera, mainly butterflies (superfamily Papilionoidea), Zygaenidae and Castniidae moths, and compare their mating behaviour with that of moth families of nocturnal habits, paying particular attention to the recently discovered butterfly-like partner-finding strategy of castniids and the fascinating facts and debates that led to its discovery.

Lantana camara L. (Verbenaceae) is a shrub of Neotropical origin that has spread to at least 60 countries (Day et al. 2003), and its ability to rapidly occupy disturbed habitat has led to it being named one of the ten worst weeds on the planet (Cronk & Fuller 1995, Sharma et al. 2005). A number of traits may have contributed to its success as an invasive species. For example, L. camara increases the available soil nitrogen in otherwise nitrogen-poor ecosystems (Sharma & Raghubanshi 2009), it is extremely resilient to disturbance (Gentle & Guggin 1997a, Hiremath & Sundram 2005), it is allelopathic to native plants (Achhireddy & Singh 1984, Gentle & Duggin 1997b) and its fruits are dispersed by a variety of birds (Mandon-Dalger et al. 2004, Swarbrick et al. 1998). A potentially unappreciated aspect of L. camara biology that may also contribute to its invasiveness relates to pollination ecology.

Surveys of the microhabitat distribution of adult butterfly species were undertaken at three rain forest sites in North Queensland, Australia, encompassing a range of rain forest vegetation types. These surveys found little evidence for a specialist canopy fauna. Most species recorded in the canopy were often seen close to the ground. At all sites, most species were observed at the edge of the rain forest habitat; within the rain forest, more species were observed near the ground than in the canopy.

Differences in behaviour, such as the mate-locating tactic, may favour the evolution of interspecific and intersexual differences in the structure of the visual system. This notion was tested by examining the relationships between eye size, body size, sex and mate-locating tactic in 16 species of butterflies. The 16 species were grouped in eight phylogenetically close pairs that differed in the mate-locating tactic displayed by the males. Eye size was characterized by eye surface area, which was estimated from a set of linear eye measurements made on 10 individuals of each sex in each species. The major findings were that eye surface area was positively correlated with body size both among and within species, males have larger eyes relative to their body size than females, and after controlling for body size and phylogeny, interspecific differences in the mate-locating tactic of males does not explain interspecific variation in the size of male eyes or in the magnitude of sexual difference in eye size. The optical and behavioural consequences of variation in eye size with body size and sex will await a better understanding of how eye structure varies with size within and between species.

The annual cycle of adult butterflies was studied at seven rocky outcrops located along an altitudinal gradient in a northern Spanish mountain area (Picos de Europa) with a Eurosiberian climate in 1993 and 1995. Both total abundance and number of species of butterflies peaked in summer at all study sites. The cumulative species number uniformly increased over the season until late summer. These results imply that butterflies concentrated their activity when temperatures were higher in the year. Regardless of their diversity and total abundance, timing of the flight period was later for assemblages at high altitude than for assemblages at low altitude. A similar trend in increasing delay in flight period was found when data were analysed separately for each species. The duration of the flight period of assemblages was correlated with abundance in 1993, but it was correlated with altitude in 1995. Most species tended to show shorter flight periods at high altitudes in both study years. These altitudinal changes in timing of adult flight are likely to be linked with effects of temperature on developmental rates of early stages of the life cycle. Changes in duration of the flight period, however, might be partly related to variability in species abundance.

Because seasonality in tropical habitats is controlled primarily by variations in rainfall rather than variations in temperature, it is frequently less predictable in timing, and spatially more patchy than seasonality in temperate habitats. This constrains the ways in which tropical species can adapt to seasonally adverse conditions, and in particular, may give greater importance to migratory behaviour as a component of seasonal adaptation.

Australian pierid and nymphalid butterflies illustrate these points. The species studied are present as adults during the dry season. Some undergo a reproductive diapause while others breed continuously. Major seasonal shifts in geographic distribution are a conspicuous feature of their biology, except in species whose reproduction is cued directly by rainfall, or are restricted to less seasonal microhabitats. Reproductive diapause is often associated with aggregation and with non-melanic polyphenism. Reasons for spending the dry season as an adult may include the fact that adult food remains available through the dry season even though larval resources disappear, and an improved capacity for opportunistic dispersal before breeding begins. The use of direct rainfall cues to control diapause may exclude non-migratory species from subtropical or temperate regions.